#include "base64_enc_dec.h"

/* Get malloc. */
#include <stdlib.h>

/* Get UCHAR_MAX. */
#include <limits.h>

#include <string.h>


size_t b64_encoded_size(size_t inlen)
{
	size_t ret;

	ret = inlen;
	if (inlen % 3 != 0)
		ret += 3 - (inlen % 3);
	ret /= 3;
	ret *= 4;

	return ret;
}

const char b64chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

char *b64_encode(const unsigned char *in, size_t len)
{
	char   *out;
	size_t  elen;
	size_t  i;
	size_t  j;
	size_t  v;

	if (in == NULL || len == 0)
		return NULL;

	elen = b64_encoded_size(len);
	out = malloc(elen + 1);
	out[elen] = '\0';

	for (i = 0, j = 0; i<len; i += 3, j += 4) {
		v = in[i];
		v = i + 1 < len ? v << 8 | in[i + 1] : v << 8;
		v = i + 2 < len ? v << 8 | in[i + 2] : v << 8;

		out[j] = b64chars[(v >> 18) & 0x3F];
		out[j + 1] = b64chars[(v >> 12) & 0x3F];
		if (i + 1 < len) {
			out[j + 2] = b64chars[(v >> 6) & 0x3F];
		}
		else {
			out[j + 2] = '=';
		}
		if (i + 2 < len) {
			out[j + 3] = b64chars[v & 0x3F];
		}
		else {
			out[j + 3] = '=';
		}
	}

	return out;
}

size_t b64_decoded_size(const char *in)
{
	size_t len;
	size_t ret;
	size_t i;

	if (in == NULL)
		return 0;

	len = strlen(in);
	ret = len / 4 * 3;

	for (i = len; i-->0; ) {
		if (in[i] == '=') {
			ret--;
		}
		else {
			break;
		}
	}

	return ret;
}

int b64invs[] = { 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58,
59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5,
6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28,
29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42,
43, 44, 45, 46, 47, 48, 49, 50, 51 };

void b64_generate_decode_table()
{
	int    inv[80];
	size_t i;

	memset(inv, -1, sizeof(inv));
	for (i = 0; i<sizeof(b64chars) - 1; i++) {
		inv[b64chars[i] - 43] = i;
	}
}

int inv[80];

int b64_isvalidchar(char c)
{
	if (c >= '0' && c <= '9')
		return 1;
	if (c >= 'A' && c <= 'Z')
		return 1;
	if (c >= 'a' && c <= 'z')
		return 1;
	if (c == '+' || c == '/' || c == '=')
		return 1;
	return 0;
}

int b64_decode(const char *in, unsigned char *out, size_t outlen)
{
	size_t len;
	size_t i;
	size_t j;
	int    v;

	if (in == NULL || out == NULL)
		return 0;

	len = strlen(in);
	if (outlen < b64_decoded_size(in) || len % 4 != 0)
		return 0;

	for (i = 0; i<len; i++) {
		if (!b64_isvalidchar(in[i])) {
			return 0;
		}
	}

	for (i = 0, j = 0; i<len; i += 4, j += 3) {
		v = b64invs[in[i] - 43];
		v = (v << 6) | b64invs[in[i + 1] - 43];
		v = in[i + 2] == '=' ? v << 6 : (v << 6) | b64invs[in[i + 2] - 43];
		v = in[i + 3] == '=' ? v << 6 : (v << 6) | b64invs[in[i + 3] - 43];

		out[j] = (v >> 16) & 0xFF;
		if (in[i + 2] != '=')
			out[j + 1] = (v >> 8) & 0xFF;
		if (in[i + 3] != '=')
			out[j + 2] = v & 0xFF;
	}

	return 1;
}

void testBase64EncodeAndDecode()
{
	//encoding
	char *bin = "Aba2s43daaJHASDB234jkkj3bKjbKJBk34j534bkjbJKB987657vt";
	size_t bin_size = strlen(bin);
	char *encoded = b64_encode(bin, bin_size);
	size_t encoded_size = b64_encoded_size(bin_size);

	//decoding
	//assuming encoded is a pointer to an array which contains the string to be decoded
	//and encoded_size is the size of the array
	size_t decoded_size = b64_decoded_size(encoded);
	char *decoded = malloc(sizeof(char) * decoded_size);
	if (b64_decode(encoded, decoded, decoded_size) != 1)
		printf("Error decoding, malformed string");

	//Testing
	if (bin_size != decoded_size)
		printf("assertion failed, sizes differ");

	int result = memcmp(bin, decoded, bin_size);
	if (result != 0)
		printf("assertion failed, string is different");
}



int hexchr2bin(const char hex, char *out)
{
    if (out == NULL)
        return 0;
 
    if (hex >= '0' && hex <= '9') {
        *out = hex - '0';
    } else if (hex >= 'A' && hex <= 'F') {
        *out = hex - 'A' + 10;
    } else if (hex >= 'a' && hex <= 'f') {
        *out = hex - 'a' + 10;
    } else {
        return 0;
    }
 
    return 1;
}

char *bin2hex(const unsigned char *bin, size_t len)
{
    char   *out;
    size_t  i;
 
    if (bin == NULL || len == 0)
        return NULL;
 
    out = malloc(len*2+1);
    for (i=0; i<len; i++) {
        out[i*2]   = "0123456789ABCDEF"[bin[i] >> 4];
        out[i*2+1] = "0123456789ABCDEF"[bin[i] & 0x0F];
    }
    out[len*2] = '\0';
 
    return out;
}

size_t hexs2bin(const char *hex, unsigned char **out)
{
    size_t len;
    char   b1;
    char   b2;
    size_t i;
 
    if (hex == NULL || *hex == '\0' || out == NULL)
        return -1;
 
    len = strlen(hex);
    if (len % 2 != 0)
        return -1;
    len /= 2;
 
    *out = malloc(len);
    memset(*out, 'A', len);
    for (i=0; i<len; i++) {
        if (!hexchr2bin(hex[i*2], &b1) || !hexchr2bin(hex[i*2+1], &b2)) {
            return -1;
        }
        (*out)[i] = (b1 << 4) | b2;
    }
    return len;
}